OVERHEATING

My van is having an overheating problem. I noticed that the van sometimes stops blowing warm air from the heater. When this happens, the van quickly overheats and lots of water leaks out. Sometimes it will overheats almost immediately and sometimes (when the heater works) it will take much longer to get overheated. The temperature will also decrease as I drive. Could this be the thermostat or something much bigger? Thanks alot for your time!

First I would check the antifreeze level. Is it low? If not then I would replace the thermostat to see if that will fix it. If that don't fix it then I would check the fan clutch to make sure it is not bad. Also check for flow it could be that the water pump isn't flowing well.